Another design solution gaining national popularity that ABMB has experience in is the Roundabout. Although new to most of the U.S. southern population, the modern Roundabout has come a long way from its origins as “traffic circles” or “rotaries” used in high density east coast cities and large metropolitan cities in Europe. Modern roundabouts, with small diameters and carefully designed entry angles, provide a slow speed environment where drivers can and do select very small gaps, often as low as one second. The design guides all traffic to flow clockwise around the circular junction and the cars within the circle are given the right of way.
This innovative and cost-effective form of "traffic calming" is designed to make permanent, physical changes to streets to slow traffic and/or reduce volumes, thus improving our safety and addressing community and business concerns. Studies show the use of roundabouts realizes a reduction of reported traffic accidents per year, a reduction of 4 to 6 miles per hour in the 85 percent percentile speeds (the speed at which 85 percent of motorists are travelling at or below), increased convenience and safety for bicyclists and pedestrians, and improved aesthetics.
ABMB designed the first roundabouts to be constructed in the Baton Rouge area on a state route. These are part of the recent relocation of River Road, and were completed in 2011. Pictures of these completed roundabouts are above, as well as a sample of the VISSIM model of the corridor which was created in the planning stage.